This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A088005 #13 Sep 21 2019 06:56:04
%S A088005 3,9,10,18,20,25,36,49,50,81,100,104,121,136,196,225,289,324,338,392,
%T A088005 464,484,576,650,676,784,800,841,900,961,968,1058,1089,1156,1225,1250,
%U A088005 1352,1682,1936,1952,2209,2312,2450,2500,2888,3136,3364,3721,4225,4356
%N A088005 Numbers whose abundance is (+-1) times a prime.
%H A088005 Amiram Eldar, <a href="/A088005/b088005.txt">Table of n, a(n) for n = 1..10000</a>
%F A088005 abs(sigma(n)-2n) is a prime.
%e A088005 n=18: sigma[18]=18+9+6+3+2+1=39, 2n=36, abundance=3, a prime;
%e A088005 n=25: sigma[25]=25+5+1=31, 2n=50, abundance=-19.
%t A088005 ab[x_] := DivisorSigma[1, x]-2*x Do[If[PrimeQ[s=ab[n]], Print[{n, s}]], {n, 1, 10000}]
%o A088005 (PARI) isok(n) = isprime(abs(sigma(n)-2*n)); \\ _Michel Marcus_, Sep 21 2019
%Y A088005 Cf. A000203, A000040, A077374, A087998.
%K A088005 nonn
%O A088005 1,1
%A A088005 _Labos Elemer_, Oct 18 2003